The "individual tuning" of the Bose system is probably just a more specific version of Nissan/Infiniti's "Driver's Audio Stage".

Basically all cars on the road have the sound system set up so it sounds like the sound is coming from the centre of the car. If you enable the "Driver's Audio Stage" the stereo system adjusts the the delays on the speakers so it sounds like the sound is coming from in front of the driver.

The "custom tuned" stereo probably involves them measuring the driver and getting a recording of how they sit in the car so they can specifically adjust the speaker delays so the sound appears to come from directly in front of them instead of using approximate measurements based on the size and seating position of the average driver.